Fig. 8. Velocity profiles (left) and vorticity profiles (right) in vertical transects through the LEV after simple freestream subtraction. Three separate wingbeats at each of the two flight speeds (1.2 m s^-1 and 3.5 m s^-1) with the light sheet at the centreline and midwing positions. In each case the peak in vorticity coincides with the centre of the portion of the velocity profiles, which are associated with solid body rotation of the vortex core. Each transect represents the horizontal component of the velocity vector, i.e. the component parallel with the freestream.